1. Field of the Invention
The present invention relates to solenoid actuators. More specifically, the present invention is directed to power control circuits for direct current solenoid valves.
2. Description of the Prior Art
Direct current (D.C.) operated solenoid valves have functional characteristics that make them unacceptable for long stroke applications. The power required for long stroke valves is very high for D.C. solenoid operators, and since with D.C. there is no impedance change from an open magnetic gap to a closed magnetic gap, the holding power is the same as the pull-in power. This produces thermal problems which can result in coil burnout. In order to enable the D.C. operated solenoid valves to be used successfully in long stroke applications, it is necessary to reduce or eliminate the thermal problem associated with the conventional long stroke D.C. operation while providing high current pull-in and low current hold in a cost effective package which could fit within the normal valve housing. Accordingly, it is desirable to provide a power management system for a D.C. valve operator solenoid to control the D.C. valve without the aforesaid problems.